The improvement of system transmission efficiency and throughput is an important issue for a communication system. A plurality of wireless connection technologies are used to improve the system transmission efficiency and throughput, such as the automatic repeat-request mechanism of Orthogonal Frequency Division Multiplexing (OFDM) system, Multiple Input Multiple Output (MIMO) system and hybrid system, where OFDM system may be against the situation of frequency selective fading channel, MIMO system may effectively increase the system efficiency and throughput, and the automatic repeat-request (ARQ) or hybrid ARQ (HARD) mechanism may provide reliably data communication on the wireless link. Hence, using the advantages of the three systems to improve the conventional communication quality is the trend for various wireless communication protocols.
In the automatic repeat-request mechanism of the conventional hybrid system, as shown in the frame format with frame type of FIG. 1, the transmission data is not distinguished into different sections for individual antennas at the transmitter. Instead, a cyclic redundancy check (CRC) 110a is added to the end of data 110b in a fixed-L-length frame 110. When applied to a multi-antenna transmission system, if error occurs in one data section transmitted from one antenna, the entire data frame must be retransmitted again. Because it must retransmit entire data, the throughput will be reduced in communication.
U.S. Patent Publication No. 2007/0255993 disclosed an Automatic Repeat-reQuest (ARQ) control system of an OFDM-MIMO communication system. The control system provides four retransmission modes for feedback information, and selects a retransmission mode to retransmit data via a retransmission mode selecting section 210a of transmitter 210. Wherein two retransmission modes transmit the data with added new data, and the other two retransmission modes in which one is to use space-time block coding (STBC) with two antennas and another is to use four antennas to transmit the data after STBC. Therefore, receiver 220 needs to use two corresponding spatial decoding techniques which are Vertical Bell Laboratories Layer Space Time (VBLAST) and STBC, shown as decoder 220a. 
Retransmission is required when error occurs during data transmission. At the transmitter, there are two ways to retransmit data. One way is permutation and interleaving retransmission (PIR) method. In other words, the permutation order of the antennas of the original data transmission will be changed in data retransmission, and interleaved in the time domain. The other way is the conjugating transformation retransmission (CTR) method. In other words, not only the antenna permutation order is changed in data retransmission, but the signals are used of complex conjugate and re-permutated.
Take N=4 as an example. Both transmitter and the receiver have four antennas. The data transmitted by each antenna uses, for example, OFDM symbol, as a unit. The four antennas transmit corresponding symbols S1-S4. FIG. 3 shows an example for the PIR method of four transmission antennas. For each data retransmission, the symbol vector transmitted by four antennas will change the original antenna permutation, and the symbols of each retransmission symbol vector will also interleave with the same order. FIG. 4 shows an example for the CTR method. For each retransmission, not only the symbol vector transmitted by the four antennas is re-permutated in accordance with the antenna order, but the signals are used of complex conjugate and re-permutated. S1*, S2*, S3* and S4* of symbol vector are the complex conjugate of symbols S1, S2, S3 and S4.
In addition to the frame type of FIG. 1, another frame type is shown as FIG. 5. In the example of FIG. 5, each fixed-L-length frame contains N transmission data sections. Individual error detection code I is added to the end of each transmission data section I, where 1≦I≦N, N is an integer greater than 1.